JP2000325862A - Coating material applying method on cylindrical base body and production of electrophotographic photoreceptor drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain excellent image characteristic on the outer peripheral surface of a cylindrical base body with a simple control. SOLUTION: In this applying method, a coating material is applied while rotating the cylindrical base body 1 and a coating roll 2 in the same direction in a non-contact state. After being transferred to the cylindrical base body 1, the coating material attains a stationary state under a condition satisfying T1<=G1 when the film thickness of the coating material on the coating roll 2 is expressed by T1 and a gap between the cylindrical body 1 and the coating roll 2 is expressed by G1, and the cylindrical base body 1 and the coating roll 2 are set apart from each other from the stationary state at a rate ranging from 50 mm/sec to 350 mm/sec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of applying a coating material to a cylindrical substrate suitable for a method of manufacturing a photosensitive drum for electrophotography.

[0002]

2. Description of the Related Art An electrophotographic photosensitive drum is provided with an undercoat layer, a charge generation layer, and a charge transport layer, which are sequentially coated and laminated on the outer peripheral surface of a hollow cylindrical substrate made of aluminum as an electrophotographic photosensitive material. In some cases, a photosensitive layer is formed.
The photosensitive layer is required to be a thin film and have a uniform thickness. However, since there is a strong demand for cost reduction, development and study of a coating method having excellent productivity are being conducted. As a method for forming a photosensitive layer by applying an electrophotographic photoreceptor coating to the outer peripheral surface of a cylindrical substrate, there have been conventionally known methods such as a spray coating method, a dip coating method, and a blade coating method. However, the conventional coating method has drawbacks such as a failure to obtain a uniform coating film and poor production efficiency.

For example, in the spray coating method, if a solvent having a low boiling point is used for the electrophotographic photoreceptor paint, the solvent contained in the paint volatilizes while the paint reaches the outer peripheral surface of the cylindrical substrate, and the solid content of the paint is reduced. Due to the increased concentration, when it reaches the cylindrical substrate, it does not spread sufficiently to the outer peripheral surface, and the coating surface becomes uneven, and the coating surface cannot be smooth and a uniform coating cannot be obtained. was there.

Conversely, when a solvent having a high boiling point is used, the paint adheres to the outer peripheral surface of the cylindrical substrate and leveling (uniformity of the film thickness, the same applies hereinafter) occurs. Fixation is delayed. Therefore, if the application is continued in a state where the coating is not sufficiently fixed, if the desired film thickness is large, paint dripping occurs, and a coating film having a uniform film thickness cannot be obtained. In order to avoid this, it is conceivable to apply the paint by dividing it into several times.However, it is conceivable to apply and dry the paint until it is dry to the touch (to the extent that no trace remains even when touched with a finger). It was necessary to repeatedly obtain a desired film thickness, which was time-consuming and extremely complicated.

According to the dip coating method, the smoothness of the surface of the coating film is improved, but the coating film is formed inside or on the end surface of the cylindrical substrate. Since the coating film formed on the inside or the end face of the cylindrical base becomes an obstacle when attaching a flange or the like, when the cylindrical base is used as a photosensitive drum for electrophotography, the coating on the inside or the end face of the cylindrical base is required. Once formed, the coating must be peeled off. Further, depending on the model used, the coating film once formed on the outer peripheral end of the cylindrical substrate must be peeled off, which requires a peeling step, which is a factor that hinders productivity.

Further, the thickness of the coating film is largely controlled by the physical properties of the coating material and the pulling speed after immersion. When the coating film is pulled at a constant speed, a difference in film thickness occurs between the upper end and the lower end of the cylindrical substrate. In order to solve this, it is necessary to control the pulling speed, but it is difficult to control it, and furthermore, it is necessary to slow down the pulling speed after immersion in order to form a uniform coating film. There was a problem, and high production efficiency could not be obtained.

[0007] The blade coating method is a coating method in which a blade is arranged at a position close to the longitudinal direction of a cylindrical substrate, paint is supplied to the blade, the cylindrical substrate is rotated once, and then the blade is retracted. Although high productivity can be obtained by this method, when the blade is retracted, a part of the coating film applied to the cylindrical substrate rises due to the surface tension of the coating material, so that the film thickness becomes uneven.

[0008]

As a method other than the above, there is a roll coating method. The roll coating method is a coating method based on supplying a coating material from a coating roll arranged at a predetermined gap to a cylindrical substrate, and thereafter separating the coating roll from the cylindrical substrate.

Japanese Patent Application Laid-Open No. 48-90746 discloses this roll coating method. According to JP-A-48-90746, a doctor roll is arranged in parallel to a cylindrical substrate, a resin is supplied to the doctor roll, and the resin is applied to the cylindrical substrate via the doctor roll. A seamless photoconductive layer with a uniform thickness is formed.

However, the level of image quality required for electrophotography has been increasing year by year. According to the study of the present inventors, only the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 48-90746 sufficiently satisfies the demand. It is becoming difficult to satisfy. In other words, the image quality required at present cannot be satisfied with the film thickness uniformity and the seam size, which were problems when the Japanese Patent Application Laid-Open No. 48-90746 was proposed.

An object of the present invention is to provide a method for forming a coating film for eliminating the drawbacks of the conventional method by a roll coating method and for efficiently obtaining good image characteristics on the outer peripheral surface of a cylindrical substrate with a simple control. As an issue.

[0012]

Means for Solving the Problems In order to solve the above problems, the present inventors have conducted detailed studies on the behavior of a coating film on a cylindrical substrate in a roll coating method. Hereinafter, this examination will be described. First, the reason why the cylindrical substrate and the application roll are rotated in the same direction in the present invention will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a cylindrical substrate as an object to be coated, and 2 denotes a coating roll, each rotating in the direction of an arrow (solid line). That is, FIG. 1 shows a case where the cylindrical base 1 and the coating roll 2 rotate in the same direction, and FIG. 2 shows a case where the cylindrical base 1 and the coating roll 2 rotate in opposite directions. Reference numeral 5 denotes a paint, which is transferred from the application roll 2 to the cylindrical substrate 1 and applied. The paint 5 is affected by the rotation direction of the cylindrical substrate 1 and the application roll 2, and each is indicated by an arrow (a chain line).
Flows in the direction of.

As shown in FIG. 2, when the cylindrical substrate 1 and the application roll 2 rotate in opposite directions, the coating material 5 applied to the cylindrical substrate 1 at the transition starting point 91 becomes the transition end point 92.
And returns to the transition starting point 91 as the cylindrical substrate 1 rotates. Therefore, a part of the paint 5 successively supplied by the application roll 2 cannot pass through the gap between the cylindrical substrate 1 and the application roll 2. The paint 5 that could not pass is accumulated near the transition starting point 91,
A paint pool 8 is formed. When the cylindrical substrate 1 is separated from the application roll 2 in this state, a portion corresponding to the coating material pool 8 protrudes and impairs the uniformity of the coating film. It is conceivable to separate the cylindrical substrate 1 from the application roll 2 before the paint pool 8 is formed.
Can not be applied uniformly over the entire outer periphery of the.

On the other hand, as shown in FIG. 1, if the rotation direction of the cylindrical base 1 and the rotation of the coating roll 2 are set to the same direction, the accumulation of paint does not occur, or even if it occurs, the amount is small.
That is, the paint conveyed by the application roll 2 is
Most of the rotation of the cylindrical body 1 from the transition starting point 91 in the direction of the arrow (chain line) reaches the transition end point 92 via the outer peripheral surface of the cylindrical body 1. Therefore, even if the paint continues to be transferred from the application roll 2 to the cylindrical substrate 1, no paint pool is generated at the transfer start point 91, or even if it is generated, the amount is small. For the above reasons, in the present invention, the cylindrical substrate and the application roll rotate in the same direction.

Next, the connection of the paint generated between the cylindrical substrate and the application roll, that is, the meniscus will be described with reference to FIG. A portion where the paint on the cylindrical substrate 1 and the paint on the application roll 2 are connected by surface tension as shown in FIG. 3 is a meniscus 9, and the cylindrical substrate 1 and the application roll 2 are connected as shown in FIG. Even if it is far away, FIG.
Even in the case where the cylindrical substrate 1 and the application roll 2 are very close as shown in (C), a meniscus 9 indicated by a hatched portion is formed due to the surface tension of the paint in any case.
The difference between FIGS. 3B and 3C is that when the thickness of the paint existing on the application roll 2 is T1, and the gap between the cylindrical substrate 1 and the application roll 2 is G1, the former is T1 <G1, and the latter is G1. Is T1>
G1. FIG. 3A also shows T1 <
G1. Further, the film thickness T1 of the paint existing on the application roll 2 refers to the thickness of a portion other than the meniscus 9.

After the paint on the application roll 2 is transferred to the cylindrical substrate 1, the present inventors make the paint into a steady state in each of the states shown in FIGS. The image quality was evaluated using an electrophotographic photosensitive drum obtained by changing the separation speed between the substrate 1 and the application roll 2 while variously changing the separation speed. It was confirmed that the electrophotographic photosensitive drum obtained by (A) and (B) had better image quality than the electrophotographic photosensitive drum obtained by FIG. 3 (C).

The present invention is based on the above findings,
In a method of applying a coating material supplied to an application roll to a cylindrical substrate, the coating material is applied while rotating the cylindrical substrate and the application roll in the same direction in a non-contact state. After being transferred to the substrate, when the thickness of the paint existing on the application roll and T1, and the gap between the cylindrical substrate and the application roll are G1, the paint is in a steady state under a condition satisfying T1 ≦ G1, In this state, the cylindrical substrate and the application roll are separated at a speed in the range of 50 mm / sec to 350 mm / sec.

Further, according to the present invention, there is provided a method for manufacturing an electrophotographic photosensitive drum in which the electrophotographic photosensitive paint supplied to an application roll is applied to a substrate of the electrophotographic photosensitive drum and then dried. The photoconductor coating for electrophotography is applied while rotating the photoconductor drum substrate and the application roll in the same direction in a non-contact state, and the electrophotographic photoconductor coating is transferred to the electrophotographic photoconductor drum substrate and then applied. Assuming that the film thickness of the paint existing on the roll is T1, and the gap between the electrophotographic photosensitive drum substrate and the coating roll is G1, the paint is in a steady state under a condition satisfying T1 ≦ G1. The photoreceptor drum base and the coating roll are moved at 50 mm / sec.
A method of manufacturing a photosensitive drum for electrophotography, wherein the photosensitive drum is separated at a speed in a range of c to 350 mm / sec.

Hereinafter, the present invention will be described in more detail. The behavior of the paint near the meniscus existing between the cylindrical substrate 1 and the application roll 2 will be described with reference to FIGS. FIG. 4
5 shows a process of separating the cylindrical substrate 1 and the application roll 2 from a steady state satisfying the condition of T1> G1, and FIG.
The process of separating the cylindrical substrate 1 and the application roll 2 from the steady state satisfying the condition of G1 is shown.

In FIG. 4, when the gap between the cylindrical substrate 1 and the coating roll 2 is increased from the steady state of T1> G1, the paint pool is formed on the meniscus 9 as shown in FIG. And remains. When the gap is further widened, the surface tension of the paint tends to maintain the meniscus 9, and as shown in FIG. 4B, the paint film thickness on the cylindrical substrate 1 decreases, and a concave portion (b) occurs. Next, as shown in FIG. 4C, when the cylindrical substrate 1 and the application roll 2 are completely separated from each other,
The joint is cut in the cylindrical substrate 1 to leave the convex portion (a), and the concave portion (b) and the convex portion (c) remain without disappearing.

FIG. 5 also shows (A) and (B) in FIG.
5, but in the case of FIG. 5, the state of FIG.
In other words, by continuously rotating while maintaining the gap between the cylindrical substrate 1 and the application roll 2 to realize a steady state in the paint, the once formed concave portion (b) and convex portion (c) are converted into the state shown in FIG.
As in (C), the degree of disappearance or remaining can be reduced. In order to obtain a steady state, it is necessary to keep rotating the cylindrical substrate 1 and the application roll 2 while keeping the gap constant. Although it fluctuates depending on various conditions such as the physical properties of the paint and the rotation conditions, at least the cylindrical substrate 1 and the application roll 2 are rotated once, preferably at least three times while the gap is fixed. Thereafter, when the cylindrical substrate 1 and the application roll 2 are completely separated from each other as shown in FIG. 5 (D), the joint is cut to form the convex portion (a) in the cylindrical substrate 1, but the degree thereof is as follows. It is smaller than in FIG. Also,
The concave portion (b) is not formed, or even if it is formed, its degree is smaller than that in FIG.

Next, the separation speed between the cylindrical substrate 1 and the application roll 2 will be described with reference to FIGS. 6 shows a case where the separation speed between the cylindrical substrate 1 and the application roll 2 is a low speed of less than 50 mm / sec, and FIG. 7 shows a case where the separation speed is an appropriate speed of 50 mm / sec to 350 mm / sec. 8 has a separation speed of 350 mm / sec
It shows the case of a high speed exceeding.

As shown in FIG. 6, when the speed at which the cylindrical substrate 1 is separated from the coating roll 2 is low, the meniscus 9 is maintained by the surface tension of the paint as the cylindrical substrate 1 is separated from the coating roll 2. In an attempt to make the paint near the meniscus be pulled by the meniscus portion, a concave portion is generated,
In addition, the length of the meniscus portion becomes longer, and the convex portion becomes larger. This phenomenon becomes more conspicuous as the separation speed is lower.

When the separation speed between the cylindrical substrate 1 and the application roll 2 is set to an appropriate value, as shown in FIG.
Therefore, even if the paint moves to maintain the above condition, the time for forming the concave portion is also reduced because the moving time is short, and the length of the meniscus portion is also reduced, and the convex portion is reduced.

However, when the speed at which the cylindrical substrate 1 is separated from the coating roll 2 is extremely high, irregular paint breakage occurs as shown in FIG. Is formed. Further, at the time of separation, the paint in the meniscus portion may entrain the air, and large bubbles may be mixed in the coating film formed on the cylindrical substrate 1.

Instead of cutting the meniscus by separating the cylindrical substrate 1 and the application roll 2, the meniscus may be cut by reducing the amount of paint on the application roll. In this case, the speed at which the paint on the application roll is reduced can be replaced with the separation speed between the cylindrical substrate and the application roll.

The thickness of the coating on the cylindrical substrate can be determined by the coating properties such as the nonvolatile content and viscosity of the coating, the coating thickness on the application roll, the peripheral speed of the cylindrical substrate and the application roll, and the like.

The thickness T1 of the paint on the application roll can be measured as follows. In other words, the surface of the application roll before application of the paint is set as a reference point (zero point) by a well-known micrometer head (of a level of 0-25 mm 0.001 mm), and when the paint is transferred, the spindle of the micrometer head is sufficiently retracted from the application roll. . Thereafter, when the paint is in a steady state, it is advanced until the spindle contacts the paint. The reading at that time is the thickness T1 of the paint on the application roll. Needless to say, the micrometer head needs to be fixed to the application roll. Further, the present invention is not limited to this method in carrying out the present invention.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 9 and FIG. 10 are a perspective view and a side view, respectively, showing an embodiment of an apparatus configuration for carrying out the present invention. 9 and 10, reference numeral 1 denotes a cylindrical substrate that is an object to be coated;
Reference numeral 2 denotes an application roll, 3 denotes a metalling roll (film thickness control means), 4 denotes a cleaning doctor, and 5 denotes a paint.

The cylindrical substrate 1, the application roll 2, and the metering roll 3 are installed so as to be rotatable in the direction of the arrow by a rotating mechanism (not shown). Further, the cylindrical substrate 1 and the application roll 2 are disposed close to each other with a gap capable of transferring the paint from the application roll 2 to the cylindrical substrate 1, and the application roll 2 and the metering roll 3 store the paint 5. They are arranged close to each other with a gap as small as possible. The paint 5 is stored in a paint storage unit 51 formed by the application roll 2, the metering roll 3, and the cleaning doctor 4 by a paint supply unit (not shown).

The coating material 5 is supplied to the outer peripheral surface of the coating roll 2 through the gap between the coating roll 2 and the metering roll 3 from the coating material storage section 51. The paint 5 supplied to the outer peripheral surface of the application roll 2 is measured based on the peripheral speed ratio between the application roll 3 and the application roll 2. Further, the surface property of the paint on the outer peripheral surface of the application roll 2 is also determined by the peripheral speed ratio.

The gap between the coating roll 2 and the metering roll 3 needs to be wider than the gap between the cylindrical substrate 1 and the coating roll 2 in order to transfer the paint to the cylindrical substrate 1 first. is there. In this case, the purpose is to transfer the paint to the cylindrical substrate 1. If the transfer is performed, the width of the gap between the application roll 2 and the metering roll 3, or the cylindrical substrate 1 and the application roll No restriction is placed on the width of the gap between the two.

By rotating the coating roll 2 and the metering roll 3 in the direction of the arrow in this state, the thickness of the coating material 5 on the outer peripheral surface of the coating roll 2 becomes uniform, so that the cylindrical substrate 1
The film thickness of the coating material applied to the outer peripheral surface becomes quickly uniform. Next, after the paint is transferred to the cylindrical substrate 1, when the coating film thickness of the cylindrical substrate 1 is stabilized, the cylindrical substrate 1 is separated from the coating roll 2 at a specified speed. At this time,
The control of the film thickness of the paint on the cylindrical substrate 1 is performed by controlling the gap between the application roll 2 and the metering roll 3, the viscosity of the paint,
It may be performed by a nonvolatile component. In the above embodiment, the metering roll 3 is rotated, but may be fixed without rotating.

In the above embodiment, the metering roll 3
The thickness of the coating 5 on the outer peripheral surface of the coating roll 2 is controlled and uniformized by using the gap between the coating roll 2 and the coating roll 2, but the coating 5 is applied to the coating 5 stored in the coating tank 52 as shown in FIG. A gap setting doctor 6 may be disposed on the application roll 2 via a gap having a predetermined width as a film thickness control means for supplying a predetermined amount of paint while dipping the roll 2. By rotating the coating roll 2 in this state, the thickness of the coating 5 on the outer peripheral surface of the coating roll 2 is made uniform, and the coating thickness can be controlled.

Further, as shown in FIG. 12, a plate-shaped film thickness control means 61 is disposed in the tangential direction of the coating roll 2 with a gap having a predetermined width, or a step is formed on the outer periphery of the cylindrical body as shown in FIG. The film thickness control means 62 provided with
And a gap having a predetermined width. According to the film thickness control means 61 and 62 shown in FIGS.
As with the gap setting doctor 6 shown in FIG.
And the coating film thickness can be controlled.

When the cylindrical substrate and the application roll are close to each other, it is in a state where they are in contact with each other via the paint to form a meniscus. The specific gap width depends on the type of the paint to be applied and the final size of the cylindrical substrate. 10 μm to
The value may be set in the range of 1000 μm and a value equal to or greater than the gap width between the application roll and the measuring means. Also, the gap width between the application roll and the film thickness control means may be set in the range of 10 μm to 1000 μm depending on the type of paint to be applied and the film thickness finally formed on the cylindrical substrate.

The peripheral speed of rotation of the cylindrical substrate when the coating material is applied is in the range of 3 m / min to 50 m / min, and the peripheral speed of rotation of the application roll is 3 m / min to 50 m / min.
It is preferable to be in the range of m / min. If the peripheral speed of the cylindrical substrate and the application roll is low, the time required for forming a coating film on the outer peripheral surface becomes long, which is not preferable for productivity. Conversely, if the peripheral speed is too high, the paint may be scattered by centrifugal force. Because.

Ratio of peripheral speed of rotation of cylindrical substrate to peripheral speed of rotation of coating roll (peripheral speed of cylindrical substrate / peripheral speed of coating roll)
Is preferably in the range of 0.5 to 2.0, and 0.6 to 1.6.
Is more preferable. If the ratio of the diameter of the coating roll to the diameter of the cylindrical substrate is in the range of 1/4 to 10, the present invention can be carried out without any problem.

After the cylindrical substrate was separated from the application roll, the rotation of the cylindrical substrate was continued while leveling and air-drying the formed coating film, and it was confirmed that even if the rotation was stopped, no paint dripping would occur. And put in a hot air circulating dryer to dry completely.

When a solvent having a relatively high volatility is used, a container, a shielding wall, or the like, in which the coating roll portion, the cylindrical base portion, or the entire periphery thereof is substantially closed in order to prevent drying due to solvent volatilization. It is also effective to cover with.

As the material of the cylindrical substrate, for example, iron,
Metals such as aluminum, copper, manganese, silicon, magnesium, zinc, stainless steel, chromium, titanium, nickel, molybdenum, vanadium, indium, gold, platinum, or alloys of these, or resins such as polyester, or resins such as polyester, are made of conductive materials such as aluminum. Examples thereof include those that are deposited, but are not limited to those listed here.

When the cylindrical substrate is a photosensitive drum for electrophotography, the photosensitive layer to be formed is a single layer type in which the charge generation material and the charge transport material are present in the same layer. It may be a stacked type in which a layer containing a charge generating material and a layer containing a charge transporting material are stacked.

The single-layer type photosensitive layer can be formed by applying a coating solution in which a charge generating material and a charge transporting material are dispersed or dissolved in a binder resin solution to the outer peripheral surface of a cylindrical substrate and then drying.

The photosensitive layer of the laminated type is obtained by applying a coating material obtained by dissolving a compound having a charge transport function in a binder resin solution onto a charge generation layer formed on the outer peripheral surface of a cylindrical substrate and then drying it to form a charge transport layer. It can be obtained by forming.
Conversely, the charge generation layer may be formed after forming the charge transport layer on the outer peripheral surface of the cylindrical substrate.

In the case of a single-layer type electrophotographic photosensitive member, the thickness of the photosensitive layer in the electrophotographic photosensitive drum is 5 to 50.
The range of μm is preferred, and the range of 15 to 40 μm is particularly preferred.

In the case of an electro-stacked electrophotographic photosensitive member, the thickness of the charge generation layer is preferably 5 μm or less, and 0.01 μm or less.
To 1 μm is particularly preferable, and the thickness of the charge transport layer is 5 μm.
The range is preferably from 50 to 50 μm, and particularly preferably from 15 to 40 μm.

The coating method according to the present invention is preferably applied to a paint having a relatively high viscosity. In the case of a single-layer type electrophotographic photoreceptor, it is preferable to apply a photosensitive layer. In such a case, it is preferable to apply the charge transport layer.

As the charge transporting material, a hole transporting material and / or an electron transporting material can be used. Examples of the hole transport material include low molecular weight compounds such as pyrene, carbazole, hydrazone, oxazole, oxadiazole, pyrazoline, arylamine, arylmethane, benzidine, thiazole, and stilbene. And butadiene compounds. Examples of the polymer compound include poly-N-vinyl carbazole, halogenated poly-N-vinyl carbazole, polyvinyl pyrene, polyvinyl anthracene, polyvinyl acridine, pyrene-formaldehyde resin, ethyl carbazole-formaldehyde resin, and ethyl carbazole. Formaldehyde resin, triphenylmethane polymer, polysilane and the like can be mentioned.

Examples of the electron transporting material include organic compounds such as benzoquinone, tetracyanoethylene, tetracyanoquinodimethane, fluorenone, xanthone, phenanthraquinone, phthalic anhydride and diphenoquinone. , Amorphous silicon, amorphous selenium, tellurium, selenium-tellurium alloy, cadmium sulfide,
Examples include inorganic materials such as antimony sulfide, zinc oxide, and zinc sulfide. The charge transporting material is not limited to those listed here, and can be used alone or as a mixture of two or more.

As the binder resin, it is preferable to use a high molecular polymer which is hydrophobic and can form an electrically insulating film. As such a high-molecular polymer, for example,
Polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile polymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acetic acid Vinyl-maleic anhydride copolymer, silicone resin, silicon-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, polyvinyl butyral, polyvinyl formal, polysulfone, and the like. It is not limited. These binder resins are used alone or in combination of two or more. Further, additives such as a plasticizer, a sensitizer, and a surface modifier can be used together with these binder resins.

Examples of the plasticizer include biphenyl, biphenyl chloride, o-terphenyl, dibutyl phthalate, diethylene glycol phthalate, dioctyl phthalate, triphenylphosphoric acid, methylnaphthalene, benzophenone, chlorinated paraffin, and various fluorohydrocarbons. .

Examples of the sensitizer include chloranil, tetracyanoethylene, methyl violet, rhodamine B, cyanine dye, merocyanine dye, pyrylium dye, and thiapyrylium dye.

Examples of the surface modifier include silicone oil, fluororesin and the like. In order to improve the adhesiveness between the cylindrical substrate and the photosensitive layer and to prevent the injection of free charges from the cylindrical substrate to the photosensitive layer, an adhesive layer may be interposed between the cylindrical substrate and the photosensitive layer, if necessary. Alternatively, a barrier layer (undercoat layer) can be provided.

When the above-mentioned charge generating material and charge transporting material are dispersed and dissolved in a binder resin solution, the solvent for dissolving the binder may vary depending on the kind of the binder, but may be one among those which do not dissolve the underlying layer. Consider choosing from.

Specific examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol and benzyl alcohol; ketones such as acetone, methyl ethyl ketone, cyclohexanone, isophorone and acetylacetone; ethers such as theolahydrofuran and anisole Amides such as N, N-dimethylformamide, N, N-dimethylacetamide; ethers such as tetrahydrofuran, dioxane, methylcellosolve, diglyme; esters such as methyl acetate, ethyl acetate, diethyl carbonate; dimethyl sulfoxide, sulfolane Sulfoxides and sulfones such as methylene chloride, chloroform, carbon tetrachloride, aliphatic halogenated hydrocarbons such as 1,1,2-trichloroethane, and the like; benzene, toluene, o-xylene, p-xylene , M- xylene, monochlorobenzene, although aromatics dichlorobenzene and the like, but is not limited thereto. These solvents are used alone or in combination of two or more.

[0057]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the scope of these examples.

(Example 1) A coating roll 2 made of carbon steel having a surface roughness of 3.2S, a length of 260 mm, and an outer diameter of 65 mm, and a metalling roll 3 of the same specifications, and a coating of hard chrome plated as a surface treatment. FIG. 9 shows the cylindrical substrate 1 as an applied material.
Were arranged as shown in FIG. The cylindrical substrate 1 is made of aluminum and has a length of 254 mm, an outer diameter of 30 mm, and a thickness of 1 mm.
Having a hollow structure. For the purpose of obtaining a photosensitive drum for electrophotography, an undercoating paint and a charge generation layer were first applied to the outer peripheral surface of the cylindrical substrate 1 by a known and commonly used means to produce a charge generation layer coated cylindrical substrate 1.

The paint for the charge transport layer has the chemical formula (1)

[0060]

Embedded image

20 parts of an arylamine compound represented by the following formula and 25 parts of a polycarbonate resin (“Iupilon Z-200” manufactured by Mitsubishi Gas Chemical Company, Inc.) were added to cyclohexanone 58
Of xylene and 58 parts of xylene.

Both ends of the cylindrical substrate 1 coated with the charge generating layer are gripped by a gripping mechanism having a bearing that is connected to a rotation driving device (not shown) and that can rotate forward and backward. The gripping mechanism is mounted on a moving device (not shown) that can move close to and away from the application roll 2 and can control the moving speed.

The charge generating layer coating cylindrical substrate 1 and the coating roll 2 are initially separated from each other, but the moving device is set so that the gap width is 200 μm during coating. The gap width between the application roll 2 and the metering roll 3 was initially set to 420 μm.

The rotation direction of the charge generating layer coating cylindrical substrate 1 and the coating roll 2 is the same direction, and the rotation direction of the coating roll 2 and the metering roll 3 is also the same direction. The peripheral speed was 10 m / min for the charge generating layer coated cylindrical substrate 1, 10 m / min for the coating roll 2, and 1 m / m for the metering roll 3.
The charge transport layer paint was supplied from the paint storage tank 51. By rotating the charge generating layer coating cylindrical substrate 1, the coating roll 2, and the metalling roll 3, a coating film having a uniform thickness was formed on the outer peripheral surface of the coating roll 2.

Thereafter, the cylindrical body 1 coated with the charge generating layer was rotated and brought close to the coating roll 2 until the gap width was reached. As a result, the coating material on the coating roll 2 was transferred to the charge generating layer coated cylindrical substrate 1 and coating was started. Immediately after maintaining the rotation state for 5 seconds from the start of the transfer, the interval between the application roll 2 and the
It was reset from 0 μm to 170 μm. After confirming that a meniscus, which is a connection between the coating material on the charge generating layer-coated cylindrical substrate 1 and the coating material on the coating roll 2, was formed, the rotating state was maintained for 11 seconds. In this state, when the thickness of the paint on the application roll 2 was measured using the micrometer head described above, the thickness was 170 μm. Then, the charge generating layer-coated cylindrical substrate 1 was set to 81.24.
They were separated at a speed of mm / sec.

The charge transport layer-coated cylindrical substrate 1 coated with the charge transport layer was air-dried while being rotated for 20 minutes as it was, and then dried at 140 ° C. for 60 minutes by a hot-air circulation dryer.

The average thickness of the dried film was measured using a high-frequency eddy current film thickness meter (“LH-300C” manufactured by Kett Science Laboratory Co., Ltd.) and found to be 31.5 μm. The difference between the maximum film thickness and the minimum film thickness of the portion corresponding to the seam portion of the paint was 2.6 μm.
The charge transport layer-coated cylindrical substrate 1 obtained above is used as an electrophotographic photosensitive drum (1).

Example 2 A charge transport layer-coated cylindrical substrate was obtained in the same manner as in Example 1 except that the charge-generating layer-coated cylindrical substrate was separated at a speed of 102.18 mm / sec. At this time, the average film thickness was 31.3 μm, and the difference between the maximum film thickness and the minimum film thickness of the portion corresponding to the joint portion of the paint when separated was 2.4 μm. This is designated as an electrophotographic photosensitive drum (2).

Example 3 A charge transport layer-coated cylindrical substrate was obtained in the same manner as in Example 1, except that the charge-generating layer-coated cylindrical substrate was separated at a speed of 215.90 mm / sec. At this time, the average film thickness was 31.7 μm, and the difference between the maximum film thickness and the minimum film thickness at a portion corresponding to the joint portion of the paint when separated was 2.6 μm. This is designated as an electrophotographic photosensitive drum (3).

Example 4 A charge transport layer coated cylindrical substrate was obtained in the same manner as in Example 1 except that the charge generating layer coated cylindrical substrate was separated at a speed of 276.00 mm / sec. At this time, the average film thickness was 31.5 μm, and the difference between the maximum film thickness and the minimum film thickness in a portion corresponding to the joint portion of the paint when separated was 1.8 μm. This is designated as an electrophotographic photosensitive drum (4).

Comparative Example 1 A charge transport layer-coated cylindrical substrate was obtained in the same manner as in Example 1, except that the charge-generating layer-coated cylindrical substrate was separated at a speed of 14.18 mm / sec. At this time, the average film thickness was 31.8 μm, and the difference between the maximum film thickness and the minimum film thickness at the portion corresponding to the seam portion of the paint at the time of separation was 4.9 μm. This is designated as an electrophotographic photosensitive drum (5).

Comparative Example 2 A charge transport layer-coated cylindrical substrate was obtained in the same manner as in Example 1, except that the charge-generating layer-coated cylindrical substrate was separated at a speed of 42.30 mm / sec. At this time, the average film thickness was 31.8 μm, and the difference between the maximum film thickness and the minimum film thickness of the portion corresponding to the joint portion of the paint when separated was 5.6 μm. This is designated as an electrophotographic photosensitive drum (6).

Comparative Example 3 A charge transport layer-coated cylindrical substrate was obtained in the same manner as in Example 1 except that the charge-generating layer-coated cylindrical substrate was separated at a speed of 417.00 mm / sec. At this time, the average film thickness was 31.6 μm, and the difference between the maximum film thickness and the minimum film thickness of the portion corresponding to the seam portion of the paint at the time of separation was 3.8 μm. This is designated as an electrophotographic photosensitive drum (7).

(Comparative Example 4) Coating was started in the same manner as in Example 1 except that the moving device was set so that the gap width was 80 μm at the time of coating. In this state, when the thickness of the paint on the application roll was measured using the micrometer head described above, the thickness was 80 μm. Thereafter, the cylindrical substrate coated with the charge generation layer was separated at a speed of 33.30 mm / sec to obtain a cylindrical substrate coated with the charge transport layer. At this time, the average film thickness was 31.2 μm, and the difference between the maximum film thickness and the minimum film thickness of the portion corresponding to the joint portion of the paint when separated was 7.0 μm. This is designated as an electrophotographic photosensitive drum (8).

(Comparative Example 5) Comparative Example 4 except that the cylindrical substrate coated with the charge generating layer was separated at a speed of 83.1 mm / sec.
In the same manner as in the above, a cylindrical substrate coated with the charge transport layer was obtained. At this time, the average film thickness was 31.6 μm, and the difference between the maximum film thickness and the minimum film thickness in a portion corresponding to the seam portion of the paint at the time of separation was 5.6 μm. This is designated as an electrophotographic photosensitive drum (9).

Comparative Example 6 A charge transport layer-coated cylindrical substrate was obtained in the same manner as in Comparative Example 4, except that the charge-generating layer-coated cylindrical substrate was separated at a speed of 215.9 mm / sec. At this time, the average film thickness was 31.7 μm, and the difference between the maximum film thickness and the minimum film thickness at the portion corresponding to the joint portion of the paint when separated was 4.0 μm. This is designated as an electrophotographic photosensitive drum (10).

Comparative Example 7 A charge transport layer-coated cylindrical substrate was obtained in the same manner as in Comparative Example 4, except that the charge-generating layer-coated cylindrical substrate was separated at a speed of 417.00 mm / sec. At this time, the average film thickness was 32.0 μm, and the difference between the maximum film thickness and the minimum film thickness of the portion corresponding to the joint portion of the paint when separated was 3.9 μm. This is designated as an electrophotographic photosensitive drum (11).

FIG. 14 summarizes the above results. As can be seen from this graph, when the paint is in a steady state under the condition satisfying T1 ≦ G1, and the cylindrical substrate and the application roll are separated from the state at a speed in the range of 50 mm / sec to 350 mm / sec, the separation occurs. It can be seen that the difference between the maximum film thickness and the minimum film thickness at the portion corresponding to the seam portion of the paint at the time becomes smaller, and becomes larger in the other range of the separation speed. Further, when the coating material is brought into a steady state under the condition of T1> G1, and the cylindrical substrate and the application roll are separated from that state, the same tendency as described above is exhibited. It can be seen that the difference between the maximum film thickness and the minimum film thickness in the portion corresponding to is large.

(Evaluation of Printing) One day after the production using the photosensitive drums (1) to (11) for electrophotography obtained from each Example and each Comparative Example, a printing test was carried out, and visual observation was performed. The electrophotographic photosensitive drums (1) to (4) had good image characteristics, but the electrophotographic photosensitive drums (5) to (11) produced uneven shading at the joints.

[0080]

According to the present invention, an electrophotographic photosensitive drum having a photosensitive layer having a uniform coating film on the outer peripheral surface of a cylindrical substrate can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a case where a cylindrical substrate and an application roll are rotated in the same direction.

FIG. 2 is a schematic diagram showing a case where a cylindrical substrate and an application roll are rotated in opposite directions.

FIG. 3 is a schematic diagram showing an example of a meniscus portion formed between a cylindrical substrate and an application roll rotated in the same direction.

FIG. 4 is a schematic view showing the behavior of a paint between a cylindrical substrate and an application roll.

FIG. 5 is a schematic view showing the behavior of a paint between a cylindrical substrate and an application roll.

FIG. 6 is a schematic diagram showing the behavior of the coating material when the separation speed between the cylindrical substrate and the application roll is low.

FIG. 7 is a schematic diagram showing the behavior of the coating material when the separation speed between the cylindrical substrate and the application roll is appropriate.

FIG. 8 is a schematic diagram showing the behavior of the coating material when the separation speed between the cylindrical substrate and the application roll is high.

FIG. 9 is a perspective view of a device configuration example for implementing the present invention.

FIG. 10 is a side view of an example of a device configuration for implementing the present invention.

FIG. 11 is a side view of another example of a device configuration for implementing the present invention.

FIG. 12 is a side view of another example of a device configuration for implementing the present invention.

FIG. 13 is a side view of another device configuration example for implementing the present invention.

FIG. 14 is a graph showing the difference between the maximum film thickness and the minimum film thickness on the cylindrical substrate when the separation speed between the cylindrical substrate and the application roll is changed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylindrical base material 2 ... Coating roll 3 ... Metalling roll (film thickness control means) 4 ... Cleaning doctor 5 ... Paint 6 ... Gap setting doctor (film thickness control means) 8) Paint pool 9 ... Meniscus

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H068 AA54 EA18 EA19 EA36 4D075 AC21 AC88 AC92 AC94 CA48 DA15 DA20 DB07 DC27

Claims (4)

[Claims] 1. A method of applying paint to a cylindrical substrate, wherein the paint supplied to an application roll is applied to a cylindrical substrate, wherein the paint is applied while rotating the cylindrical substrate and the application roll in the same direction in a non-contact state. After the paint is transferred to the cylindrical substrate, if the thickness of the paint present on the application roll is T1, and the gap between the cylindrical substrate and the application roll is G1, T1 ≦ G1
The coating material is brought into a steady state under the conditions satisfying the following conditions, and the cylindrical substrate and the coating roll are moved from 50 mm / sec to 3 mm from that state.
A coating method for coating a cylindrical substrate, wherein the coating is separated at a speed in a range of 50 mm / sec. 2. The method according to claim 1, wherein the steady state is obtained by maintaining G1 constant. 3. A method of manufacturing a photosensitive drum for electrophotography, comprising applying the photosensitive coating material for electrophotography supplied to a coating roll to a photosensitive drum base for electrophotography and then drying the coating. The photoconductor coating for electrophotography is applied while rotating the roll in the same rotation direction in a non-contact state, and the electrophotographic coating for electrophotography is transferred onto the photoconductor drum base for electrophotography and is present on the application roll. Assuming that the film thickness of the electrophotographic photoreceptor paint is T1, and the gap between the electrophotographic photoreceptor drum base and the application roll is G1, T1 ≦ G1
The electrophotographic photoreceptor paint is made to be in a steady state under the condition satisfying the condition, and the electrophotographic photoreceptor drum base and the application roll are separated from the state at a speed in the range of 50 mm / sec to 350 mm / sec. A method for manufacturing an electrophotographic photosensitive drum. 4. The method according to claim 3, wherein the steady state is obtained by maintaining G1 constant.